This is an unpublished "white paper" where Mattson reviews the use of road density standards for grizzly bears, "the primary standard for management of grizzly bear habitat in the contiguous United States."

"Currently we conceive of human-bear contact manifesting itself in 2 primary ways:
(1) habitat alienation or avoidance; and
(2) mortality risk."

Mattson argues that "no one road density standard is appropriate for all ecosystems or areas" because:
- bears in areas that range wider are at greater risk to roads;
- depending on human tolerance of bears, the risks to bears from roads will vary;
- mortality risk due to roads will vary due to vegetative cover in an area;
- the presence of closed roads and trails will influence effects of open roads.

"-Including a 2-km buffer, the absolute minimum size for a roughly circular "security area" in the Yellowstone ecosystem should be ca. 28 km2 (ca 5,400 acres)."
"-If an entire Yellowstone Bear Management Unit were apportioned to minimum-sized security areas, ca. 10% of the unit would be sufficiently buffered to maintain high levels of wariness, corresponding to an average road density of 0.4 km/km2."

"-To secure ca. 50% of available habitat in a Yellowstone BMU, road densities would need to be ca. 0.16 km/km2"

"No grizzly bear population has been known to persist for an extended period of time (>3-4 generations) in areas uniformly characterized by high levels of human access, in the range of 0.50-1.0+ km/km2 road densities."

"-My conclusion for the Yellowstone area is: Averaged over a BMU subunit, road densities >0.40 km/km2 are not likely to be compatible with long-term persistence of the grizzly bear population. Averaged over an entire BMU, road densities >0.16 km/km2 are also not likely to be compatible with long-term persistence of the bear population. Areas with greater road densities have a high probability of being population sinks."